# Tag Info

5

The main requirement here is temperature resistance. A 3D printer extruder is very, very hot, and will easily exceed the ratings of many typical silicone glues in normal service or during a runaway event. (You should always plan for an eventual thermal runaway. They're alarmingly common with cheap kit printers.) Even high-temp glues will not survive the ...

5

The most common choice for insulating thermistors is glass fiber sleeving. It tolerates very high temperatures, and is commonly rated for up to 600 °C. Teflon is also used but has a rather low upper limit on its working temperature; it shouldn't be used at temperatures exceeding 260 °C - which rules it out for your purpose.

4

After replacing the control board, it now prints flawlessly. Apparently,I really did damage the control board...

4

I'm not sure if it fits the use you're describing, but Kapton (polyimide) tape is stable to about 400 degrees C. It can also be used as a build surface, so generally useful to have some. Kapton tape is used all the time for electronic work, both to secure fine wires (for example patch wires on a PCB) and for insulation. It's not so great for thermal ...

4

This can come from several sources: Hardware The thermistor or its connections might be damaged, and the fault is only observable when the hotend is hot or moved to a certain area. Start by checking the wiring! You may be able to repair a bad connection easily, but depending what was broken, you may need to replace something. In some cases squishing a ...

4

I had the same issue. Hot-end temperature reading stuck at 209 degrees even with hot-end thermistor disconnected or swapped with bed thermistor on the Anet A8 mainboard. After ordering and swapping the AtMega1284p (using jtagice3 and hot-air soldering station) and the 4.7 Kohm resistor (which measured 2.06Kohm on the board and 4.7kohm off the board) to no ...

4

In pins_RAMPS.h you find which pins are used for which thermistor: // // Temperature Sensors // #define TEMP_0_PIN 13 // Analog Input #define TEMP_1_PIN 15 // Analog Input To use the other thermistor, you would need to swap the numbers: // // Temperature Sensors // #define TEMP_0_PIN 15 // Analog Input #define TEMP_1_PIN ...

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You can use kapton tape, small PTFE tube, or silicone tape. I use PTFE on my delta printer (I do have a silicone tape wrapped around my heat block, but that's to help with keeping the heat in the block, not for eletrical insulation (although it would work for that)). These will all handle the temperatures of your heat block fairly well.

4

Thermal runaway protection (see What is Thermal Runaway Protection?) is triggered when the scheduled voltage to the heater element does not result in a specified increase in temperature within a specified timeframe. The exit of hot filament from the nozzle and the loss of heat of the heater block and the conduction heat loss through the heat break to the ...

4

Safety First Let's look at the graphs. First: you should swap firmware for one that has Thermal Runaway, as, as it is, running about 15 minutes with 28 K less than the printer is ordered to work at is a clear indication that there is no Thermal runaway protection in place - it should have tripped over that long ago! But there is more! Problem But this graph ...

3

A brand new thermistor shows about 95-105k ohm (depends on the multimeter quality), so it looks like that one is out of the range. To be sure that it is a thermistor, you could connect a 100k potentiometer, play with it and see readings on the lcd. If the readings are OK, then mainboard is good so replace the thermistor. A 100k thermistor curve

3

One of the thermistor wires had come loose from the crimp ferrules. I re-crimped it and it works fine now.

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This sounds like a problem I had with my hotend cooling fan a couple years back. To answer your question, from what I'm reading, the Prusa3D firmware detects thermal runaway if the hotend temperature drops for more than 45 seconds, it detects an open-circuit by reading 16 °C or less (MINTEMP error), and detects a short by reading 310 °C or ...

3

and found out it has a resistance of 1.5kΩ, while it should have a resistance of 4.7kΩ, so I suspect this is the main reason behind this high reading. Now the only thing left to figure out is how the resistance of this resistor changed. You can't measure the resistance of a resistor in circuit - the resistance probably appears to be lower to your multimeter ...

3

The main problem here is that the hot block has to match the temp sensor. There are a couple available commercial options for hotblocks with cartridge-and-setscrew temp sensors, but they're not thermistors: E3D PT100 RTD -- requires a special amp (http://e3d-online.com/V6-PT100-Sensor-Kit) Carl Raffle Tecto Heater Block with thermocouple -- works as-is in ...

3

My thermistors came with a small spring surrounding them, which seems to work pretty well for this (see also E3D Thermistor Alternative). It's pretty close to the size of the spring in an ordinary pen, so you could just try one of those, or you could wind one from copper wire. I always use thermal grease as well, just like you'd use for heat sinks. image ...

3

I am not too sure what you're searching for, but I imagine it to be a kind of thermistor housing to distribute pressure from the screw while maintaining good heat conductance. I first have to say that I'd be afraid to damage the glass droplet of the typical thermistor design by putting pressure to them, especially including later thermal expansion. However, ...

3

This depends on how you ended up with your finished printer. If it was a kit, then there is a chance that the thermistors might be the same, however, even a kit manufacturer might buy parts that come preassembled as I could imagine being the case for the hotend. To find out about the actual thermistor you would need to look up the spec sheet of the ...

3

I got my printer fixed and am posting steps I took for people with similar problems in the future. Initial problem: After I replaced my entire heating unit and reconnected the wires, my printer started to read about 135/185 °C for the nozzle and bed at room temperature. It gives the "Heating failed, printer halted, please reset" error when I tried to heat ...

3

Most thermosensors are functionally nothing different but a temperature dependant resistor. As such, our boards usually use $U=RI$ to get to the resistance, and then compare that to a temperature table. In effect, they put in a regulated potential difference, and measure how much current flows. Plugging this into $U/I=R$ gives the Resistance, which then ...

3

Yes, thermistors can drift in value as well as outright failing (usually open). In my experience this is not uncommon in thermistors operated above 100 degrees C. The drift is typically downward in resistance so the controlled temperature will be less than the desired setpoint, which is exactly what you are observing.

2

It doesn't make a great deal of difference where you place the thermistor; do whatever is most convenient for you. The temperature of the heated bed is not very critical, and some inaccuracy in the measurement is perfectly fine. The point is to keep the print from cooling down too fast, and whether the bed is at 95C or 93C makes little difference. The pros ...

2

Depending on thermistor type you can get values from around 1ohm/C to 0.01ohm/C so placing it on particulat place on heatbed (HB) could be very important. If objects are placed in the center then it's quite obwious that thermistor should be placed also in the middle. Another issue in terms of thermistors are the wires. Because thermistors can be so ...

2

I like the mounting method on my Mk9 extruder: there's a small hole drilled into the heat block, parallel to the heater hole. B3 Innovations sells a thermistor packaged into a small spring. The whole assembly goes in the hole, and a setscrew (gently!) secures it. You could just as well put a bare thermistor into a spring or something similar; it's mainly to ...

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Ok, so I think I have found the answer. You can get cotton wraps for print heads with some Kapton tape on them, see 10Pcs 3mm Thickness 3D Printer Heating Cotton Hotend Nozzle Heat Insulation. I think this will work best as long as it doesn't catch on fire. Please let me know if there is a better alternative but for now I will use these.

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For an illustration of how to employ the Kapton tape, that is mentioned in the answers from Harvey Lim and Howler, watch How to build a RepRap Prusa i3 (Assembly 7) at 21:30: From 15:10 the heater and thermistor is connected up, you may find this also useful. Note that, at 20:45, the heatshrink is only used over the soldered connection, and not all the way ...

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I used Kapton tape to insulate mine.

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Thermistors, commonly used as temperature sensors on 3D printers and other DIY things, work by changing their internal resistance depending on the temperature. On the analog ports, the microcontroller can determine the voltage of the connected signal. To actually measure the resistance - and thus temperature - of the thermistor, you need to build a voltage ...

2

You could use Kapton tape to tape the thermistor. It is usually the best option for sticking something onto the hotend or on the heat block. You will also have less trouble since it is very thin. Note that if you use Kapton tape, you should use several layers of it for added insulation.

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There are many unknowns at this point, you need to work methodically through each stage. You probably also need some test equipment, at least a basic multimeter. Ideally a temperature probe too. First, check that your power supply can drive the hot-end directly. You already know how long it takes to reach 120°C, so be sure to not let it heat too far beyond ...

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